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Improvements in and relating to unloading valves for hydraulic pumps

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  • Title:
    Improvements in and relating to unloading valves for hydraulic pumps
  • Author: Towler John Maurice ; Towler Frank Hathorn
  • Subjects: Performing Operations ; Transporting ; Presses ; Presses In General ; Medicine ; Sciences ; Chemistry
  • Language: English
  • Description: 788,928. Hydraulic presses. ELECTRAULIC PRESSES, Ltd. May 28, 1954 [June 12, 1953; July 10, 1953], Nos. 16206/53 and 19156/53. Class 69 (2). In an hydraulic press, supplied with liquid by more than one continuously running pump, a relief valve connected to the press cylinder actuates a selector valve controlling unloading valves so that the pumps are loaded and unloaded according to the pressure in the press cylinder. The selector valve is as described in Specification 727,804 and is actuated by hydraulically-operated pawl-and-ratchet mechanism 1-13, controlled by a solenoid-operated valve 14. The ratchet-wheel carries contact strips BD; BL. When the relief valve closes, it actuates a switch whereby one of two solenoids A, B is energized, the valve 14 moved, and liquid admitted to one of two cylinders 9, 10 whereby one of the pawls moves the disc 1 on the selector valve. When the relief valve opens, the discharge passes through a choke, and backpressure operates a switch which moves the valve 14 in the opposite direction, and the disc 1 is turned in the reverse direction. A hand control can be pre-set to load or unload the pumps when the selector valve has been moved by the pawl-and-ratchet mechanism to the preset position. Micro-switches ME, MF, MH, MG are provided in the electrical circuits operating the solenoids A, B. The switches are engaged by the pawls 2, 3. Two further microswitches are provided and are operated by the pressure-relief valve. The relief valve may be as described in Specification 783,413.
  • Creation Date: 08 January 1958

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